It is known that functional group-terminated polymers may undergo crosslinking, either by themselves or in the presence of another polymer having a terminal or chain-interrupting functional group and an appropriate curing agent depending on the properties of functional groups, to give functional products having outstanding heat resistance, water resistance, durability, compatibility and other characteristics. Moreover, when a polymer has functional groups at all its molecular termini, a chain extension by terminus-terminus crosslinking occurs with good efficiency to give a linear or network high molecular weight polymer and, hence, a resin with excellent elongation and tensile strength characteristics.
Functional group-terminated polymers are of great use as, for example, reactive raw materials for resins such as polyester resin, polyurethane resin, polycarbonate resin, etc., paints, adhesives, self-adhesives, sealants, urethane foams, gel coatings, thermoplastic elastomers, molding compounds, resin modifiers, dampers, elastic wall and floor panels, textile processing agents, UV•EV-curable resin, high-solid paints and so forth. These are also useful as various resin additives and raw materials.
Referring to rubber type polymers among functional group-terminated polymers, many reports are available on their syntheses until now. Moreover, these have been used as starting materials for urethane adhesives and sealants which having a functional group at both termini of a polyether backbone chain or modifiers for epoxy adhesives. In addition, polyester resins such as polyethylene terephthalate and polycaprolactone have also been used in many applications. However, as too other resins, particularly those of vinyl monomers having polar groups, the production method for functional group-terminated vinyl polymers has not been implemented on a commercial scale as yet.
As for a production method of polymers of such functional group-terminated highly polar vinyl monomers, for example, Japanese Kokai Publication Hei-5-255415 discloses a process for synthesizing a (meth) acrylic polymer having an alkenyl group at both termini by using an alkenyl group-containing disulfide as a chain transfer agent. Japanese Kokai Publication Hei-5-262808 discloses a process comprising synthesizing an acrylic polymer having a hydroxyl group at both termini by using a hydroxyl group-containing disulfide and utilizing these terminal hydroxyl groups, synthesizing an alkenyl group-terminated (meth)acrylicpolymer. However, in the former process, a functional group can hardly be introduced into the terminus with certainty and the latter process requires a chain transfer agent in a large amount for synthesizing a hydroxyl group-containing polymer. Thus, these synthetic technologies have drawbacks in some process parameters or others.
Recently much research has been undertaken on the polymerization by the living polymerization method inclusive of living ionic polymerization and living radical polymerization. In the synthesis of polymers by these polymerization techniques, the molecular weight and molecular weight distribution can be controlled and, moreover, by converting the active group at the living terminus to a desired substituent group, a functional group-terminated polymer can be produced with comparative ease.
Referring to the production method of a functional group-terminated polymer by utilizing the above-mentioned living ionic polymerization method, Japanese Kohyo Publication Hei-4-501883, for instance, discloses a process for synthesizing a hydroxyl group-terminated poly(meth)acrylic ester and a process for synthesizing a (meth) acrylic acid macromonomer by way of living anionic polymerization. However, in the case of such anionic polymerization, the termination reaction and chain transfer reaction cannot be controlled unless anhydrous or low-temperature conditions are maintained and the reaction does not proceed in the living fashion so that the terminal transformation is rendered impossible. Therefore, the technology is lacking in commercial utility.
Referring to living radical polymerization, Japanese Kokai Publication Hei-9-272714, for instance, discloses a production method of an alkenyl group-terminated (meth) acrylic polymer which comprises using an organohalogen or brominated sulfonyl compound as an initiator and an equivalent amount thereto of a complex of a Group 8 to 11 transition metal as a catalyst. However, the transition metal complex has such a high affinity for oxygen that unless in a completely inert system its catalytic activity is lost to arrest the progress of polymerization. Therefore, the technology is not practically useful as for a production.